氧氣分析儀PMA30：

Application
Due to the extremely fast response time
of the patented M&C magneto-dynamic
measuring cell with no stagnant volume
as well as the negligible cross sensitivity
from other sample gas components,
the portable M&C oxygen analyser PMA 30
has a wide variety of applications.
The analyser is a suitable and reliable instrument
for monitoring oxygen concentrations
in various gas analytical control applications
including flue gas-, inert gas-, fermentation
processes- and process or laboratory control
measurements.
Description
The M&C oxygen analyser PMA 30 is a temperature
controlled instrument which has
been designed for continuous measurements
of oxygen concentrations in particle-free and
dry sample gas.
The PMA 30 is a reliable and easy-to-operate
instrument. It is built into a compact 19
inch cassette. The transducer unit maintains
a constant operating temperature of 50 °C
and a flashing LED on the control panel indicates
the proper operating temperature of
the analyser. The five measuring ranges are
displayed on the analogue meter with 30/
scale. The PMA 30A/D has a combined
analogue/digital meter and the PMA 30/D
has only a digital meter. Two output signals
are available. Sample gas connections as well
as connectors for incoming power supply,
output signals, remote ranging, remote range
indication and status contact are located at
the rear panel of the analyser. The sample
gas enters the analyser via an external protective
fine-filter. The required flow rate can
be adjusted at the flowmeter with needle
valve, mounted on the front panel upstream
the M&C measuring cell and the flow alarm
sensor. The internal tubing is made of PTFE
and PVDF.
Measuring principle of M&C oxygen
analyser
The PMA 30 utilises the paramagnetic principle
of operation to measure oxygen concentrations.
The analyser measures the paramagnetic
susceptibility of the oxygen in the
sample gas by means of the M&C magnetodynamic
measuring cell. The physical propertys
which distinguishes oxygen from other
gases is its paramagnetism. It is significantly
higher comparing to other common gases.
This operation principle is one of the most
accurate and reliable procedures to determine
the oxygen concentration in a gas mixture
from 0 to 100 Vol.%.
The robust M&C cross-flow cell has no
stagnant volume. Advantages are the fast
response time, the flow rate up to 60 l/hr,
the small volume of 2 ml, the extremely low
drift, the absolute linearity and the negligible
cross sensitivity against other sample gas
components. With a proper sample conditioning
and pressure, the M&C cell will never
need replacing. The dumbbell with a small
mirror at its centre is mounted in a strong
inhomogenous magnetic field. The paramagnetic
oxygen strengthens the forces on the
diamagnetic dumbbell and causes a shifting
which is detected by a system consisting
of light beam, mirror and a photo cell.
A compensation current is induced via the
feedback coil on the dumbbell and leads to
a reset of the dumbbell into its zero-position.
The required current is linearly proportional to
the oxygen concentration.